In traditional heavy oil recovery employing steam injection, the produced water, oil and gas flow together from the wellhead to the process factory. The produced fluids generally form an oil-water emulsion. At the process factory, the traditional process is to separate the gases and oil from the water. The oil is then treated to remove trace amounts of water and other materials to meet the required sales specification. Generally, the oil produced in thermal recovery schemes is high in density and viscosity. Therefore, a diluent, such as condensate, naphtha, light crude oil or synthetic oil is added to the produced oil to reduce the density and viscosity to meet the pipeline specifications. The water that has been separated from the oil requires additional treatment to remove the entrained oil to very low levels to ensure that it does not foul downstream water treatment systems. To produce a water quality suitable to feed drum boilers or Once Through Steam Generators (OTSG's), field process techniques treat the de-oiled water using either a combination of ion exchange and lime softening to remove inorganic solids and reduce water hardness; or an evaporator which boils and subsequently condenses the water to produce a water that is very low in dissolved and suspended inorganic solids. In the former case, the water is suitable as boiler feed water to an OTSG to produce steam for the thermal recovery process. In the latter case, the water purity can be suitable for use in a drum boiler or an OTSG. However, both of these prior art techniques require the steps of water separation and treatment which involve considerable expense, manpower and equipment. Thus, none of the prior art steam generation techniques have been entirely satisfactory.